Adjustable square.



' UNITED STATES PATENT OFFICE.

LAROY S. STARRETT, OF ATHOL, MASSACHUSETTS, ASSIGNOR TO THE L. S.STARRETT COMPANY, OF ATHOL, MASSACHUSETTS, A CORPORATION OFMASSACHUSETTS.

ADJUSTABLE SQUARE.

SPECIFICATION forming part of Letters Patent No. 715,703, dated December9, 1902.

Application filed. May 3, 1901 Serial No. 58,572. (No model.)

To aZZ whom it may concern.-

Be it known that I, LARoYS. STARRETT, of Athol, in the county ofWorcester and State of Massach usetts, have invented certain new anduseful Improvements in Adjustable Squares, of which the following is aspecification.

The object of this invention is to provide an accurate try-square havinga clamping stock or head and a thin tempered blade either graduated orplain and adapted to project at one or both sides of the stock or head,being adjustable with relation thereto and furnished with a clampingdevice adapted to prevent loss of the blade when the clamp is loosened,my invention providing for a short or long working blade up to its fulllength, with movement but one-half of it.

My present improvement is embodied in a square having a thin temperedblade either plain or graduated on one or both edges of its oppositefaces and formed with an elongated slot through it midway between itsedges and closed at both ends in combination with a rectangular stock orhead deeply grooved at one end to form a seat for such blade andperforated endwise in the plane of said groove, and with a clampingdevice comprising a bolt or stud in said perforation having a laterallug near one end, fitting loosely in the slot of the blade, such bolt orstud being threaded at its opposite end to receive a milled nut adaptedto turn in a recess in said head, and a spiral spring surrounding suchthreaded stud between said nut and head to hold the blade frictionally.

In the drawings, Figure 1 is an elevation of the tool complete. I Fig. 2is a vertical crosssection in the plane of the clamping-screw; and Fig.3 is a view of the parts detached, the bolt, nut, and spring being shownenlarged.

A represents the stock or head (a rectangular casting) having a thinwebor central portion, thickened and parallel margins, and at one end athickened longitudinal boss B midway between its edges, the web beingcut away or recessed at the end of the boss. The end of the stock orhead has a deep groove or recess O to admit the blade edgewise, and aperforation D in the same plane through said boss to receive theclamping-bolt. foration is of reduced diameter at foot to conform to thesmaller part'of the bolt.

E is the blade, (a thin strip of tempered steel,) preferably graduatedto different scales on one or each edge of one or both itsfaces. Throughthis blade I form a slot F through the thin metal, the edge walls ofsaid slot and blade being perpendicular to the faces. The slot runs froma point near one end of the blade to or beyond the middle thereof, sothat the blade may extendadj ustably in either direction. The slot is ofuniform width without enlargement at any point and is closed at bothends.

G is a clamping-screw the stem of which occupies the perforation D andis formed with a lateral lug H near its outer end to enter and traversethe slot F of the blade. As seen in Figs. 2 and 3, the stem of screw Gis cut away laterally below and above the lug H, so that the blade E mayfit closely against these fiat faces of the stem and the prolonged headand be held very firmly, the lug transversely filling the perforationD.

J is a milled nut engaging the threaded end of screw G and recessed toreceive a spring K, which surrounds the screw. The upper end of thisspring bears against the bottom of the boss 13, so that its downwardpressure on the nutJwill tendto draw the blade downwardly. V

In assembling the parts the screw-bolt G is placed transversely on thebladeE with the lug H in the slot F. The screw is then inserted inperforation D, the edge of the blade in groove 0, and the nut withspring applied to the screw-tip. Tightening the nut draws down the bladeand holds it firmly in its seat in the end of head A. When the nut isslackened, the blade is held with a yielding pressure, due to theinterposed spring K. Thus the blade may be adjusted at different lengthseither way, while the closed ends of the slot prevent endwise detachmentof the blade, thus making a try-square with the blade available for usefrom nothing up to its full length, while the blade is slotted but abouthalf its length.

This per- My present improvement enables me to use alight thinspring-tempered blade, which on account of its thinness and hardnesscould not be grooved like the thicker soft blades, as in the adjustablesquares shown in my former patent, (now expired,) which I have made foryears and still manufacture. The light spring-tempered blades arepreferable and more cheaply made, While the lug extending through theopen slot, closed at its ends, makes a much better and stronger hookconnection than the short lip in the groove of my former patent or asheretofore made. The lug ILtransversely filling the perforation D,excludes dust and prevents any sidewise movement of the clamping-bolt.

I claim as my invention 1. In an adjustable square, the rectangularstockor head A having continuous, raised, parallel edges, a thickenedlongitudinal boss inclosing the screw-bolt, and a thin central Webconnecting said edges and boss and recessed transversely to receive theclam pingnut, such stock or head being formed with the endwise groove, 0and perforation, D, reduced in diameter at bottom, in combination withthe blade E, having closed slot F in said groove, and the screw-bolt Gin said perforation, with its lug, H, in said slot and transverselyfilling the perforation, the threaded portion of said bolt being reducedin diameter to pass through the smaller end of perforation D, and with aclamping-nut on the screw-tip in said recess, substantially as setforth. r

2. The described adjustable square, comprising the rectangular stock orhead, A, with transverse recess for the clamping-nut, end- Wise groovefor the blade and perforation for the clamp-screw in the same plane, incombination With blade E, having closed slot, F, of uniform WidthWithout enlargement, the edge walls of said blade and slot beingperpendicular to its face, the screw-bolt, G, With its lug, H, in suchslot, and transversely filling said perforation, and its head, of abouthalf-diameter, prolonged above the lug, the recessed clamping-nut, J, onthe screw-tip, and the spring, K, in said nut-recess, substantially asset forth.

In testimony whereof I have affixed my signature in presence of twoWitnesses.

LAROY S. STARRETT. Witnesses:

DAVID FINDLAY, FRANK E. WING.

